125-200cc Make My Sms Cylinder Perform Like A Cr/wr One.

Hi, I've been riding a Husky SMS 125 '07 (7 ports cyinder) for the last two years, and I want to prepare the motorbike (mikuni 38, pvl stator, mechanic exhaust valve, etc.) I know that are 144cc available, but they are very expensive moreover are only 5 ports; so I definately discard getting one.

I've been planning to prepare the whole engine: file and polish the crankcase, and prepare the cylinder to be like the cr or wr cylinder. But as my mother tongue isn't English (despite I can keep a Conversation, when I hit some technical words I end up lost), could you please tell me the difference between the sms/wre cylinder and the wr/cr one? And what should I do, besides rising 2 or 3mm the intake ports, to make my cylinder perform like a cr/wr one?

Thank you from spain!